In this study, we examined survival for patients with micrometastases greater than 0.2mm but less than 2mm (pN1a) in comparison to node-negative (pN0) and macrometastatic node-positive (pN1b) patients. Data for patients diagnosed from 1988 to 1998 with TNM pathological T1-2 stage, pN0, and pN1a-b breast cancer with no distant metastasis was provided by Dr. P. Truong from BC Cancer Agency. Results obtained from the Kaplan-Meier estimators and the multivariable Cox Proportional Hazards Model analyses suggested that micrometastatic node-positive patients had worse survival than the node-negative patients, but better survival in comparison to the macrometastatic node-positive patients. Increasing number of positive nodes and larger values of the ratio of positive to excised nodes were significantly associated with worse survival.

Background: Laparoscopic surgery for colorectal cancer is a novel healthcare technology, for which much research evidence has been published. The objectives of this work were to compare the oncologic outcomes of this technology across different study types, and to define patterns of adoption on the basis of the literature. Methods: A comprehensive systematic review of the literature was conducted using 1) existing systematic reviews, 2) randomized controlled trials (RCTs), and 3) observational studies. Outcomes of interest were overall survival, and total lymph node harvest. Outcomes were compared for congruence. Adoption was evaluated by means of summary expert opinions in the literature. Results: 1) Existing systematic reviews were of low to moderate quality and displayed evidence of overlap and duplication. 2) Laparoscopy was not inferior to open surgery in terms of oncologic outcomes in any study type. 3) Oncologic outcomes from RCTs and observational studies were congruent. 4) Expert opinion in the literature has been supportive of this technology, paralleling the publication of large RCTs. Conclusions: The evaluation of laparoscopic surgery for colorectal cancer in RCTs and observational studies suggests that it is not inferior to open surgery. Adoption of this technology has paralleled RCT evidence.

Sensor networks are innovative wireless networks consisting of a large number of low-cost, resource-constrained sensor nodes that collect, process, and transmit data in a distributed and collaborative way. There are numerous applications for wireless sensor networks, and security is vital for many of them. However, sensor nodes suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the lack of infrastructure, all of which impose formidable security challenges and call for innovative approaches. In this thesis, we present our research results on three important aspects of securing sensor networks: lightweight entity authentication, distributed node clone detection, and secure data aggregation. As the technical core of our lightweight authentication proposals, a special type of circulant matrix named circulant-P2 matrix is introduced. We prove the linear independence of matrix vectors, present efficient algorithms on matrix operations, and explore other important properties. By combining circulant-P2 matrix with the learning parity with noise problem, we develop two one-way authentication protocols: the innovative LCMQ protocol, which is provably secure against all probabilistic polynomial-time attacks and provides remarkable performance on almost all metrics except one mild requirement for the verifier's computational capacity, and the HB$^C$ protocol, which utilizes the conventional HB-like authentication structure to preserve the bit-operation only computation requirement for both participants and consumes less key storage than previous HB-like protocols without sacrificing other performance. Moreover, two enhancement mechanisms are provided to protect the HB-like protocols from known attacks and to improve performance. For both protocols, practical parameters for different security levels are recommended. In addition, we build a framework to extend enhanced HB-like protocols to mutual authentication in a communication-efficient fashion. Node clone attack, that is, the attempt by adversaries to add one or more nodes to the network by cloning captured nodes, imposes a severe threat to wireless sensor networks. To cope with it, we propose two distributed detection protocols with difference tradeoffs on network conditions and performance. The first one is based on distributed hash table, by which a fully decentralized, key-based caching and checking system is constructed to deterministically catch cloned nodes in general sensor networks. The protocol performance of efficient storage consumption and high security level is theoretically deducted through a probability model, and the resulting equations, with necessary adjustments for real application, are supported by the simulations. The other is the randomly directed exploration protocol, which presents notable communication performance and minimal storage consumption by an elegant probabilistic directed forwarding technique along with random initial direction and border determination. The extensive experimental results uphold the protocol design and show its efficiency on communication overhead and satisfactory detection probability. Data aggregation is an inherent requirement for many sensor network applications, but designing secure mechanisms for data aggregation is very challenging because the aggregation nature that requires intermediate nodes to process and change messages, and the security objective to prevent malicious manipulation, conflict with each other to a great extent. To fulfill different challenges of secure data aggregation, we present two types of approaches. The first is to provide cryptographic integrity mechanisms for general data aggregation. Based on recent developments of homomorphic primitives, we propose three integrity schemes: a concrete homomorphic MAC construction, homomorphic hash plus aggregate MAC, and homomorphic hash with identity-based aggregate signature, which provide different tradeoffs on security assumption, communication payload, and computation cost. The other is a substantial data aggregation scheme that is suitable for a specific and popular class of aggregation applications, embedded with built-in security techniques that effectively defeat outside and inside attacks. Its foundation is a new data structure---secure Bloom filter, which combines HMAC with Bloom filter. The secure Bloom filter is naturally compatible with aggregation and has reliable security properties. We systematically analyze the scheme's performance and run extensive simulations on different network scenarios for evaluation. The simulation results demonstrate that the scheme presents good performance on security, communication cost, and balance.

In den letzten Jahren wurde die Sentinel Node Biopsie in Studien zur Diagnostik und Behandlung des N0-Halses als Stagingverfahren untersucht. Ziel der vorliegenden Studie war der Vergleich der postoperativen Lebensqualität und des funktionellen Status bei Patienten mit oralen und oropharyngealen Karzinomen, die sich einer Sentinelbiopsie, bzw. einer selektiven Neck Dissection bei N0-Hals unterzogen haben. 57 Patienten mit primär operativ behandeltem Karzinom wurden im Rahmen der Studie untersucht, 29 nach Sentinel Node Biopsie und 28 nach selektiver Neck Dissection. Es wurde die postoperative gesundheitsbezogene (EORTC QLQ-C30) und krankheitsspezifische Lebensqualität (EORTC QLQ-H&N35) erfasst. Patientenbezogene psychosoziale Variablen wurden anhand der „Hospital Anxiety and Depression Scale“ (HADS) und der Kurzform des „Progredienzangst-Fragebogens“ (PA-F-KF) ermittelt. Die Erhebung des klinischen Gesundheitszustandes erfolgte unter besonderer Berücksichtigung des funktionellen Status nach zervikaler Lymphknotendissektion. Bezüglich der gesundheitsbezogenen Lebensqualität sowie der Angst und Depression existierten keine signifikanten Unterschiede. Hinsichtlich der krankheitsspezifischen Lebensqualität zeigte sich, dass die Patienten nach Sentinel Node Biopsie weniger Schluckbeschwerden angaben (p=0,037). Ebenso zeigte sich bei der klinischen Untersuchung eine geringere Beeinträchtigung durch die zervikalen Narben. Die Sentinel Node Biopsie bietet, neben dem geringeren operativen Aufwand, der schnelleren Rekonvaleszenz und der geringeren funktionellen Minderung der Patienten, eine tendenzielle Verbesserung der krankheitsspezifischen Lebensqualität. Als Grund für die subjektiv weniger beeinträchtigte Schluckfunktion kann die fehlende Präparation der suprahyoidalen Muskulatur und der entsprechend innervierenden Nerven in Erwägung gezogen werden.

With recent and continuing advances in bioinformatics, the volume of sequence data has increased tremendously. Along with this increase, there is a growing need to develop efficient algorithms to process such data in order to make useful and important discoveries. Careful analysis of genomic data will benefit science and society in numerous ways, including the understanding of protein sequence functions, early detection of diseases, and finding evolutionary relationships that exist among various organisms. Most sequence analysis problems arising from computational genomics and evolutionary biology fall into the class of NP-complete problems. Advances in exact and approximate algorithms to address these problems are critical. In this thesis, we investigate a novel graph theoretical model that deals with fundamental evolutionary problems. The model allows incorporation of the evolutionary operations ``insertion', ``deletion', and ``substitution', and various parameters such as relative distances and weights. By varying appropriate parameters and weights within the model, several important combinatorial problems can be represented, including the weighted supersequence, weighted superstring, and weighted longest common sequence problems. Consequently, our model provides a general computational framework for solving a wide variety of important and difficult biological sequencing problems, including the multiple sequence alignment problem, and the problem of finding an evolutionary ancestor of multiple sequences. In this thesis, we develop large scale combinatorial optimization techniques to solve our graph theoretical model. In particular, we formulate the problem as two distinct but related models: constrained network flow problem and weighted node packing problem. The integer programming models are solved in a branch and bound setting using simultaneous column and row generation. The methodology developed will also be useful to solve large scale integer programming problems arising in other areas such as transportation and logistics.

Doctor of Philosophy (PhD) / Sensor networks have great potential to be employed in mission critical situations like battlefields but also in more everyday security and commercial applications such as building and traffic surveillance, habitat monitoring and smart homes etc. However, wireless sensor networks pose unique security challenges. While the deployment of sensor nodes in an unattended environment makes the networks vulnerable to a variety of potential attacks, the inherent power and memory limitations of sensor nodes makes conventional security solutions unfeasible. Though there has been some development in the field of sensor network security, the solutions presented thus far address only some of security problems faced. This research presents a security framework WSNSF (Wireless Sensor Networks Security Framework) to provide a comprehensive security solution against the known attacks in sensor networks. The proposed framework consists of four interacting components: a secure triple-key (STKS) scheme, secure routing algorithms (SRAs), a secure localization technique (SLT) and a malicious node detection mechanism. Singly, each of these components can achieve certain level of security. However, when deployed as a framework, a high degree of security is achievable. WSNSF takes into consideration the communication and computation limitations of sensor networks. While there is always a trade off between security and performance, experimental results prove that the proposed framework can achieve high degree of security with negligible overheads.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Thesis (MSc (Geography and Environmental Studies))--University of Stellenbosch, 2005. / The morphological form of South African cities is deemed inefficient and fragmented. Much of the current structure has been shaped by i) the political history of the country, with major influences from the colonial and apartheid eras; and ii) suburban sprawl influenced by the use of private vehicles. This presents obstacles to the sustainable and equitable development of our cities. Since the 1990s, efforts have been made to change the development of the country in order to accommodate previously disenfranchised communities through processes of reconstruction and development. Among these efforts are policies and frameworks aimed at guiding the development and growth of cities. Among the many approaches that have been identified are land use strategies, with the central focus of promoting densification and intensification of urban development. Emphasis on densification in certain public transport corridors and decentralised nodes are in general regarded as urban restructuring elements necessary to transform South African cities into efficient and sustainable areas. However, analytical tools that can explore the possibilities and limits of public transport-orientated development are scarce at present. The University of Utrecht in the Netherlands has developed an analytical model referred to as the node-place model, which can be used to profile nodes and to determine their (re)development potential. This study makes a contribution towards efforts to support the densification concept in general and nodal intensification in particular by applying the node-place model to a selection of railway stations in the Cape Town metropolitan area in order to identify appropriate land use developments to enhance their potential. The model was found to be a useful mechanism for comparing nodes within a transport system for purposes of informing decisions regarding how the nodes should be developed. However, the model requires more accurate and disaggregated data than is generally available for the Cape Town area.

RANKL (ligand du récepteur activateur de NF-KB) est un membre de la famille des TNF dont la signalisation passe par RANK et qui joue un rôle important dans la régulation immunitaire. Chez l'adulte, RANKL est exprimé constitutivement par des cellules réticulaires marginales (MRC) des ganglions lymphatiques. Comme les MRCs sont physiquement proches des lymphocytes B (LB) et ont été proposé d’être des précurseurs de cellules dendritiques folliculaires (FDC), RANKL pourrait jouer un rôle dans la différenciation du stroma associé aux LB et dans la réponse humorale. Afin de mieux comprendre la fonction de RANKL exprimé par les MRC, nous avons généré des souris déficitaires pour RANKL dans les cellules stromales. Nous avons constaté que la formation du follicule B était perturbée ainsi que le réseau FDC. Bien que RANKL ne soit pas requis pour la formation des MRC, il est nécessaire pour l'expression de la chimiokine CXCL13 par ces mêmes cellules. Parmi les TNFRSF dont la signalisation est requise pour l’expression de CXCL13 et la différenciation des FDC, le TNFR1 était significativement réduit dans les cellules stromales des souris dépourvues de RANKL stromal. Ainsi, RANKL pourrait constituer une nouvelle cible thérapeutique contre les immunopathologies des LB en agissant sur son stroma. / RANKL (receptor activator of NF-κB ligand), a member of the TNF family that signals via RANK, plays an important role for immune regulation. In the adult, RANKL is constitutively expressed by marginal reticular cells (MRCs) of the lymph nodes. Because MRCs are positioned in close vicinity to B cells and may be precursors of follicular dendritic cells (FDCs), RANKL could play a role in the differentiation of B cell-associated stroma and the humoral immune response. In order to better understand the role of RANKL expressed by the MRCs, we generated mice with conditional RANKL deficiency in the stromal compartment. We found that the B cell follicle structure was disrupted and FDC network formation was reduced. Although RANKL was not required for MRC formation, it was necessary for the expression of B cell attracting chemokine CXCL13. Among the TNFRSF members known to control CXCL13 expression and FDC formation, we found that TNFR1 was significantly reduced in the RANKL cKO mice. Thus, RANKL may present a novel therapeutic strategy against B cell-mediated immunopathologies by acting on its stroma.

This thesis proposes an implementation of battery-powered, time-synchronized wireless nodes that can be deployed in a wireless network topology. Wireless sensor networks are used in a wide variety of scenarios where emphasis is placed on the wireless nodes’ battery life. The main area of focus in this thesis is to examine how wireless nodes can save battery power by utilizing a deep sleep mode and wake up simultaneously using time synchronization to carry out their data communication. This was achieved by deploying five time-synchronized, battery-powered nodes in a wireless network topology. The difference in battery current draw between continuously running nodes and sleep-enabled nodes were measured, as well as the time duration needed by the nodes to successfully send their payloads and route other nodes’ data. The nodes needed between 1502 ms and 3273 ms on average to carry out their data communication, depending on where they were located in the network topology. Measurements show that sleep-enabled nodes on average draw substantially less current than continuously running nodes during a complete data communication cycle. When sleep-enabled nodes were powered by two AA batteries, an increase in battery life of up to 1800% was observed.